After stroke, both isometric and isokinetic trunk muscle strength has been found to be impaired. As sensory input is required for motor performance and skill acquisition, this study examined whether transcutaneous electrical nerve stimulation (TENS), combined with trunk training, can enhance trunk control after stroke.

Forty-six patients with a history of stroke of at least six months' duration, and with impaired balance, were studied. All patients received task-related trunk training (TRTT). Patients in the treatment group also received treatment with a TENS unit, with electrodes placed over the latissimus dorsi and the external abdominal oblique on the affected side. For placebo stimulation (placebo-TENS) the electrical circuitry inside the TENS unit was disconnected. The subjects were assessed at baseline (A0), after three weeks of training (A1), after six weeks of training (A2) and at four weeks after intervention termination (Afu). Trunk motor control was quantified using the Trunk Impairment Scale (TIS).

Compared to the control group, both the TENS and the placebo-TENS groups showed greater improvements in average isometric peak trunk flexion and extension torques, lateral seat reaching distances and TIS scores at A1, A2, and Afu. When compared with the placebo-TENS group, the TENS + TRTT group showed earlier and greater improvement in mean TIS scores at A1 (P<0.05). At A2, the active TENS, but not the inert TENS group showed significant improvements in forward and lateral seated reach distance scores and TIS scores. Post hoc analysis revealed that both TENS groups demonstrated significant improvement in dynamic sitting balance.

This study found that home-based, task-related trunk training is effective for improving trunk strength, sitting functional reach and trunk motor control, with the addition of TENS units augmenting the effectiveness of these exercises.